Bone marrow metastasis in Ewing's sarcoma and peripheral primitive neuroectodermal tumor: An immunohistochemical study

Bone marrow metastases from small round cell tumors can present diagnostic difficulties. In this study, we assessed the value of immunohistochemistry, using two monoclonal antibodies to CD99, for the diagnosis of metastatic disease in bone marrow trephine specimens from patients with Ewing's sarcoma or primitive neuroectodermal tumor (PNET). The proportions of specimens showing metastases were 10.3% with routine staining and 20.7% with immunohistochemistry. The specimens that were negative on conventional light microscopy and positive with immunohistochemistry all showed other abnormalities. The results do not support the routine use of immunohistochemistry in specimens that are normal by conventional light microscopy, but indicate that useful information may be gained in cases where marrow histology is obscured by fibrosis, necrosis, or distortion artefact. Neither of the two antibodies tested was superior for this purpose

Primary lymphoma of the gallbladder

A case of primary lymphoma of the gallbladder is described which is rare in the medical literature. A 76 year old man presented with acute cholecystitis and septicaemia. Investigation showed a lung abscess and a gallbladder mass. The mass was thought to be an empyema and cholecystostomy was performed. Biopsy of the gallbladder wall showed high-grade B cell lymphoma. The patient unfortunately succumbed to overwhelming septicaemia in the postoperative period. Postmortem examination confirmed primary lymphoma of the gallbladder without dissemination

Reproducibility and accuracy of MR imaging of the brain after severe birth asphyxia

BACKGROUND AND PURPOSE: MR imaging of the brain can be used to detect cerebral damage after suspected hypoxic-ischemic injury. This study examines the reproducibility and accuracy of MR imaging soon after severe birth asphyxia. METHODS: During a 48-month period, full-term newborn neonates, who died within the first week as a result of severe hypoxic ischemic encephalopathy, were included in the study if they had undergone early (<5 days old) MR imaging and postmortem neuropathologic studies. Two trained observers assessed reproducibility by examining multiple brain regions independently with current criteria and then defining and applying improved criteria. Accuracy of MR findings was tested by comparing the brain regions about which the two imaging raters agreed to those regions about which the two pathologists agreed. RESULTS: Eight neonates, with a median gestational age of 40 weeks (range, 38−40 weeks) and who suffered severe birth asphyxia, were included in the study. In the reproducibility study, MR imaging agreement was moderate when current criteria were used (k = .44). Using the improved criteria, agreement increased considerably (k = .62). Much of this improvement was due to limiting the analyses to the posterior limb of the internal capsule, thalamus, parietal cortex, hippocampus, and medulla. The posterior limb of the internal capsule was the most reliable region analyzed. MR imaging agreement was similar to that achieved by two experienced pathologists reviewing the histologic sections (k = .66). In the accuracy study, MR imaging abnormality was predictive of pathologic abnormality with a sensitivity of .79 and a positive predictive value of 1.0. The predictive value of a single MR imaging abnormality was .79 (95% confidence interval, .61−.96). CONCLUSION: Criteria that provide substantial reproducibility and accuracy for the interpretation of MR imaging findings very early after birth asphyxia can be derived

A mouse model of tuberous sclerosis 1 showing background specific early post-natal mortality and metastatic renal cell carcinoma

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in either the TSC1 or the TSC2 genes and characterized by the development of benign hamartomatous growths in multiple organ systems. We have inactivated Tsc1 in the mouse germ line by gene targeting in ES cells and confirmed that the mutant allele (Tsc1−) has a recessive embryonic lethal phenotype. We found that a significant number (∼27%) of heterozygous (Tsc1+/−) mice on the C57BL/6 background died before weaning (P=0.014) and show that these mice die in the post-natal period (P=0.033), normally at 1–2 days, from unknown causes. Forty-four percent (7/16) of Tsc1+/− mice on a C3H background developed macroscopically visible renal lesions as early as 3–6 months, increasing to 95% (37/39) by 15–18 months. Renal lesions progressed from cysts through cystadenomas to solid carcinomas. Eighty percent (16/20) of Tsc1+/− mice on a Balb/c background exhibited solid renal cell carcinomas (RCC) by 15–18 months and in 41%, RCCs were ≥5 mm, resulting in grossly deformed kidneys. Some RCCs had a sarcomatoid morphology of spindle cells in whorled patterns and metastasized to the lungs. We detected loss of the wild-type Tsc1 allele and elevated levels of p-mTOR and p-S6 in lesions from Tsc1+/− mice. This new murine model of hamartin deficiency exhibits a more severe phenotype than existing models